Trimming mechanism for sewing machines



April 18, 1939. F. M. CARD TRIMMIX IG MECHANISM FOR SEWING MACHINES 2 Sheets-Shet 1 Filed Feb. 17, 1938 gwvewkov fieder zb 1% 6 41 62 April 18, 1939.

F. M. CARD 2,155,301

TRIMMING MECHANISM FOR SEWING MACHINES Fi led Feb. 17, 1958 2 Sheets-Sheet 2 flederzb 17/. arr-a2? WLV LGM: 1 %77 2% W W,

Patented Apr. 18, 1939 UNITED STATES TRIBE/LING MECHANISM FOR SEWING MACHINES Frederic M. Gard, Bridgeport, Conn, assignor to The Singer Manufacturing Company, Elizabeth, N. 3., a corporation of New Jersey Application February 17, 1938, Serial No. 190,918

Claims.

This invention relates to trimmer mechanisms for sewing machines and particularly to trimmer mechanisms of the so-called Barber type in which a horizontally vibratory cutter-blade 5, has a depending fin provided with a cutting edge intermittently effective to trim sheet material.

The present invention has for its primary object to provide a sewing machine with a Barber trimmer mechanism adapted to smoothly trim m sheet material regardless of whether or not the successive cuts made by the horizontally vibratory cutter-blade are in alinement.

A further object of the invention is to provide an improved actuating mechanism for a commercially well known Barber trimmer mechanism of a'sewing machine.

With these and other objects in view, as will hereinafter appear, the present invention comprises the devices, combinations and arrangements of parts as hereinafter described in connection with the accompanying drawings which illustrate a preferred embodiment of the, invention and in which:

Fig. 1 is a front elevation, partly in section,

of a sewing machine having the present improved trimming mechanism. Fig. 2 is a side elevation of a portion of the bracket-arm standard as viewed from the needle side thereof, the bedplate being sectioned'substantially on the line 2-2 of Fig. 1. Fig. 3 represents a vertical section, on a reduced scale, of the bracket-arm head of the machine. Fig. 4'represents a detail view, in perspective, of the trimmer-knife and its carrier.

The sewing machine illustrated in the drawings herewith is commercially well known and corresponds, in all essential details, with the machine more fully illustrated and described in the U. S. patent to W. C. Van Ness et al., No.

40 1,884,404, Oct. 25, 1932. l V

Referring to the drawings, the sewing machine has a frame comprising a bed-plate I from one end of which rises the hollow standard 2 supporting a tubular bracket-arm 3, which termi- 45 nates in a head 4 and overhangs the bed-plate l. Disposed directly below the bracket-arm head 4 is a Work-supporting post 5 rising from the bedplate I. I v

Journaled in the bracket-arm 3 is a rotary needle-reciprocating shaft 6 having a crank-disk 1 connected by means of a link 8 with a needlebar 9 carrying at its lower end a needle 10. The needle-bar 9 is journaled for endwise reciproca tion in vertically alined bearings providedin' a 55 frame l l, journaled upon a pivot-pin I2 for swinging work-feeding movements of the needle it] about an axis substantially parallel to the needle-reciprocating shaft 6.

The needle-bar frame II is operatively connected with a crank-arm 13 on one end of a horizontally disposed rock-shaft 14, said rockshaft 14 being journaled in the bracket-arm 3 below and substantially parallel to the shaft 6 from which it derives its rocking movements, as more fully disclosed in said prior Patent No. My 1,884,404.

Cooperating with the needle ID in the formation of lock-stitches is a vertical-axis rotary hook I5 within the upper end of the work-supporting post '5. The rotary hook I5 is carried by the up- 15.

per end of a vertically disposed loop-taker shaft I5, journaled in bearing-lugs within said post 5 and carrying at its lower end a bevel-gear l1. Meshing with the bevel-gear I1 is a bevel-gear 18 carried by one end of a loop-taker actuating 20 shaft l9 horizontally journaled below and in suitable bearings depending from the bed-plate I. In the present instance, the bevel-gears I1 and 18 are proportioned so that the loop-taker shaft [6 rotates twice for each rotation of the 26 loop-taker actuating shaft l9. At its other end the loop-taker actuating shaft l9 carries another bevel-gear 20 engaged by a bevel-gear 2| carried by the lower end of a vertically disposed intermediate shaft 22. The intermediate shaft 30 22 extends upwardly within the bracket-arm standard 2 and, as disclosed in said prior Patent No. 1,884,404, is operatively connected to the needle-reciprocating shaft 6 to rotate in one-toone relation therewith.

Cooperating with the needle 10 in advancing the work is a feed-wheel 23 projecting through the upper end of the work-supporting post 5. The feed-wheel 23 rotates continuously during the operation of the machine and is driven from the intermediate shaft 22 by suitable connections therewith substantially as disclosed in said prior Patent No. 1,884,404. Opposed to the feedwheel 23 is a roller-presser 24 of any usual or suitable construction.

Combined with the sewing machine hereinbefore described is a trimmer mechanism corresponding substantially to that disclosed in the U. S. patent to J. C. Binge, No. 1,585,691, May 25, 1926. This trimmer mechanism includes a horizontally vibratory trimmer-knife 25 having a' depending lip 26 provided at one end with a cutting edge 21. The knife 25 is adjustably secured by screws 28 to a carrier-arm 29 extending horizontally from the disk-head 30 of a vertically disposed and tubular rock-shaft 3|, the carrier-arm 29 being secured by screws 32 in a recessed seat in the upper face of the head 30.

The rock-shaft 3| is journaled in bearing-lugs 33 and 34 projecting from the side wall of the post 5 proximate to the machine standard 2. Clamped upon the lower end of the rock-shaft 3|, below the bearing lug 34, is a bent crank-arm 35 provided at its free end with a vertically socketed boss 36 in which is disposed a vertically mov-- able latch-member 31; is yieldingly depressed by a spring 38 limited in its effective action by the latch-member head 31' which engages one end of a latch-lever-39 extending between the latch-member head 31' and the upper end of the boss 36. The latchelever 39 is fulcrumed between its ends upon a screw 40 threaded into the crank-arm 35, and at its other end engages the shouldered lower end of a release-rod 4| disposed for vertical movement within the rock-shaft 3|. The release-rod 4| projects through and above the rock-shaft head 38 and is provided at its upper end with a button 42 which may be manually depressed to lift the latch-member engaging end thereof against the action of the spring 38. r

' The work-supporting post 5 has two vertically spaced lugs 43 and 44 directly below the post-lug 34, said lugs 43 and 44 being provided with vertically alined apertures affording a bearing for a short rock-shaft 45 in vertical alinement with the rock shaft 3 The upper end of the rock-shaft 45 has a bore 45' to provide clearance for the lower end of the release rod 4| when depressed.

Clamped upon the rock-shaft '45, between the lugs 43 and 44, is an actuating crank-arm 46, and depending rigidly from the free end of said crankarm 46 is a forked-member 47 embracing an auxiliary fork 47' which'issuitably swiveled to the fork 4'! for turning movements therein about an axis substantially parallel to the rock-shaft 45. The auxiliary fork 4'| embraces a slide-block 48 which is pivotally secured by a pivot-bolt 49 to the upperarm of a rock-lever 50 fulcrumed, I

between its ends, upon a pivot-pin 5| supported by a bracket 52 suitably secured to the under side of the bed-plate if The forked lower arm of the rock-lever 58 embraces a cam 53 carried bya tubular shaft 54 rotatably journaled upon and coaxial with the loop-taker actuating shaft l9, said tubular shaft 54 being confined by two collars, as 55, against movement lengthwise of the shaft|9j k I Secured upon the tubular shaft 54 to rotate therewith is a pulley 56 connected by a belt 51 to the smaller pulley 58 'of'asubstantially constantspeed electric motor 59. The electric motor 59 is preferably supportedby a bracket 66 secured by screws, as 6|, to the rear wall of the machine standard 2. The operation of the motor 59 may be'started and stopped by means of any suitable switch 62 and a suitable housing 63 is preferably provided for the belt 51.

" From the foregoing description it will be understood that when the electric motor 59 is in operation, the tubular shaft 54 will be rotated, the driving connections being preferably such that said tubular shaft 54 rotates in the direction of rotation of the loop-taker actuating shaft 19. The cam 53 carried by the tubular shaft rocks the lever 56 about the pivot-pin 5|, thereby rocking the crank-arm 45. The crank-arm 46 is apertured at its free end to receive the lower end of' the spring-pressed latch-member 31 which serves" disconnectibly to connect the crank-arms The latch-member 3T 46 and 35. When said crank-arms are thus connected, the rock-shaft 3| is actuated to vibrate the trimmer-knife 25 at a substantially constant speed. i

The latch-member 31 may be withdrawn from latching engagement with the crank-arm 46, during the operation of the machine, by depressing the release-rod 4|, thereby rocking thelatch-lever 39 to lift the latch-member 31 against the action of the spring 38. Embracing the rock-shaft 3| is ac'oil-spring 64 of which one end engages a collar 65 secured to the rock-shaft 3| and the other end is anchored to the post 5. When the latch-member 31 is released from the crank-arm 46, the spring 64 functions to turn the rock-shaft 3| in a direction to swing the trimmer-knife 25 rearwardly into an inoperative position determined by a suitable stop (not shown). A finger-piece 66 is clamped upon the rock-shaft 3| to provide convenient means for returning the trimmerknife 25 into operative position wherein the latch-member 31 again engages the crank-arm 46. The usual work-guide 61 is preferably employed and requires no further comment.

The speed of operation of the sewing machine is operator controlled, as usual, so that the rate of advance of the work under combined'action of the feed-wheel 23 and the needle I!) is suitable to the character of the work. While the trimmer knife 25 vibrates at a substantially constant speed, its frequency of vibration should preferably be substantially one-to-one with the frequency of needle-reciprocation at high speed operation of the machine. When stitching in sharp curves, the sewing machine must be slowed down sufiiciently to permit the operator to handle the work, but the trimmer-knife 25 then continues .to vibrate with the same frequency as before, so that said trimmer-knife makes a plurality of cuts for each needle-reciprocation. This condition greatly improves the appearance of the trimmed workmargin. 7

It will be noted that the described trimmerknife actuating connections constitute a simple combination of the ply-separating trimmer'mechanism of U. S. Patent No. 1,585,691 with the commercially well known sewing machine of U. S. Patent No. 1,884,404, in a manner to obtain the advantageous variable ratio of needle and trimme'r-knife frequencies characteristic of the mechanism'disclosed in the U. S. Patent to F. M. Card, No. 2,105,347, Jan. 11,1938. 1 a

. Having thus'set forth the nature of the invention, what I claim herein is:

1. In a sewing machine, a reciprocatory needle, a loop-taker complemental to said needle in the formation of stitches, a rotary loop-taker actuating shaft, means for rotating said loop-taker actuating shaft, a trimmer-knife having effective work-severing movements adjacent said needle, a tubular trimmer-knife actuating shaft rotatably journaled upon said loop-taker actuating shaft,

1y of said needle-reciprocating mechanism for rotating said trimmer-knife actuating shaft.

3. In a sewing machine, a reciprocatory needle, a loop-taker complemental to said needle in the formation of stitches, a rotary loop-taker actuating shaft, means for rotating said loop-taker actuating shaft, a vibratory trimmer-knife having effective work-severing movements adjacent said needle and its axis of vibration substantially parallel to the path of needle reciprocation, a trimmer-knife actuating shaft journaled coaxially with said loop-taker actuating shaft and rotatable relatively thereto, operative connections with said trimmer-knife actuating shaft for V1- brating said knife, and means for rotating said trimmer-knife actuating shaft.

4. The combination with a sewing machine having a work-support, a bracket-arm overhanging said work-support, stitch-forming mechanism including a reciprocatory needle, and mechanism supported by said bracket-arm for reciprocating said needle, of a trimmer mechanism including a vibratory trimmer-knife having effective worksevering movements adjacent said needle, a trimmer-knife actuating shaft rotatably journaled below said work-support, and means operable independently of said needle-reciprocating mechanism for rotating said trimmer-knife actuating shaft.

5. A sewing machine having, in combination, a frame including a bed-p1ate,a work-supporting post rising from said bed-plate, and a bracketarm overhanging said work-supporting postfa reciprocatory needle, mechanism mounted on said bracket-arm for reciprocating said needle,'a loop-taker disposed within said work-supporting post and complemental to said needle in the formation of stitches, means including a rotary shaft 'journaled below said bed-platefor actuating said loop-taker, a vibratory trimmer-knife having its axis of vibration extending lengthwise of said post, a tubular shaft rotatablyjournaled upon the loop-taker actuating shaft, operative connections with said tubular shaft for vibrating said knife, an electric motor operable independently of said needle-reciprocating mechanism, and connections with said electric motor for rotating said tubular shaft.

, FREDERIC M. CARD. 

